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Description
Bismuth silicate (Bi4Si3O12, BSO) crystal is a promising inorganic scintillator for the electromagnetic calorimeters of future high-energy physics experiments. It offers stopping power and density comparable to those of bismuth germanate (Bi4Ge3O12, BGO), together with a faster decay time, greater radiation hardness, and lower raw-material cost. Large, high-quality BSO crystals are nevertheless difficult to grow, as the melt is only near-congruent and lies close to the eutectic point of the Bi2O3–SiO2 system. The two starting oxides, Bi2O3 and SiO2, also differ greatly in melting point and density. The longest BSO crystal reported to date is only 210 mm. Here we fabricated three large BSO crystals from ingots grown at the Shanghai Institute of Ceramics (SIC), Chinese Academy of Sciences (CAS). Their dimensions are 22.6 mm × 22.6 mm × 369 mm (SIC-BSO-369), 18.6 mm × 18.6 mm × 259 mm (SIC-BSO-259), and Ø36 mm × 167.4 mm (SIC-BSO-167). We characterized their optical transmittance, photoluminescence, X-ray excited luminescence, light output, energy resolution, and light response uniformity. For the fully polished, ESR-wrapped SIC-BSO-259 crystal, the light response uniformity δ measured at the seed end and the tail end was (-1.19 ± 0.50)% and (-0.52 ± 0.50)%, respectively. Both values are smaller in magnitude than the ±2% reported previously for BSO crystals of 188 mm and 187 mm. Both values are better than the ±2% reported previously for BSO crystals of 188 mm and 187 mm. The optimum δ values for the remaining two crystals were (1.41 ± 1.78)% for Tyvek-wrapped SIC-BSO-369 and (0.73 ± 1.15)% for ESR-wrapped SIC-BSO-167. These results extend the reported BSO crystal length from 210 mm to 369 mm and strengthen the case for it as a cost-effective alternative to BGO crystal in future electromagnetic calorimeters.
